Cordless telephones typically comprise a base unit and a handset. The base unit is typically connected to a telephone network through a telephone line interface. The handset is typically coupled with the base unit via an RF link. For example, conventional cordless telephones have an RF link in the 46-49 MHz frequency range, and more recent cordless telephones have an RF link in a frequency band near 900 MHz. The RF link between the handset and the base unit is typically divided into two portions, such as an uplink from the handset to the base unit at a first frequency, such as 46 MHz, and a downlink from the base unit to the handset at a second frequency, such as 49 MHz.
Cordless telephone handsets typically incorporate a user input mechanism, such as a keypad, through which a user inputs information, such as a telephone number corresponding to an outgoing telephone call. A processor, such as a microprocessor, digital signal processor (DSP), application specific integrated circuit (ASIC), or logic within the handset interprets the user input and communicates the user input via the uplink to the base unit where it is in turn processed and/or forwarded to the telephone network through the telephone line interface. Thus, when placing an outgoing telephone call, a user typically enters, via the keypad, the telephone number to be called. The processor in the handset typically processes the user input and communicates the input telephone number to the base unit via the uplink. The base unit typically includes a processor, such as a microprocessor, DSP or ASIC, that creates a signal, such as a dual tone multifrequency (DTMF) signal, which corresponds to the key of the keypad activated by the user, and is output to the telephone network via the telephone line interface. By receiving a series of DTMF signals, the telephone network is thus alerted to the user's intention to initiate an outgoing call, and informed of the number to which the outgoing call is desired.
Cordless telephone handsets also typically include a microphone and a speaker respectively positioned internal to a mouthpiece and an earpiece. When communicating during a telephone call, a user speaks into the microphone in the mouthpiece and listens to audible sounds produced by the speaker in the earpiece. Typically, sounds produced by the user are converted into electrical signals by the microphone. In an "analog" configuration, these electrical signals are then typically transmitted via the uplink to the base unit. In a "digital" configuration, on the other hand, the electrical signals are digitized by an analog-to-digital (A/D) converter, processed by the processor in the handset, and transmitted as digital signals via the uplink to the base unit. In the analog configuration, the base unit forwards the electrical signals to the telephone network via the telephone line interface. In the digital configuration, on the other hand, the base unit processor processes the digital signals, which are then converted to analog signals by a digital-to-analog (D/A) converter and then forwarded to the telephone network via the telephone line interface.
An advantage of a cordless telephone, when compared to a conventional corded telephone, is that the cordless telephone allows a user to "roam" while entering into or engaging in a telephone call. The area within which the user can roam is limited by the RF link. Typically, the range of the RF link allows a user to roam throughout a house and within a surrounding area while maintaining connectivity via the RF link to the base unit. The range of more recent cordless telephones has been further extended to more than a kilometer. As long as the user is within range of the base unit, the user can place and receive telephone calls via the handset.
The ability to roam with the telephone handset results in a unique set of problems. For example, a roaming user may be a distance from the base unit when a telephone call is completed, and after completing the telephone call the roaming user may place the handset down in a convenient location. At a later time, when the user wishes to place an outgoing telephone call, the user may forget the location where the user placed the handset, and thus be unable to locate the handset. To address this problem, some cordless telephones include a "page/find" feature, through which the user presses a button on the base unit (which, because it is connected to the telephone line interface, is stationary, and thus its location is presumably always known by the user) to cause the handset to emit an audible alarm to enable the user to locate the handset.
Frequently, a user of a cordless telephone may roam within a television viewing area, such as a family room, while engaged in a telephone conversation. When a s telephone conversation ends, the user may place the handset in a convenient location, such as on top of a coffee table or an end table proximate to a couch or chair within which the user was sitting during the telephone conversation. This convenient location may also be the present location of one or more remote control units associated with home entertainment equipment, such as a television, a stereo, a videocassette recorder (VCR) or other audio/video equipment. This situation presents many problems.
For example, when the user is alerted by a sound such as a telephone ring to the presence of a new incoming telephone call, the user must distinguish between the remote control unit(s) and the cordless telephone handset to determine which device is the cordless telephone handset. This can be a difficult task, especially if the user is engaged in nighttime television viewing in a low illumination setting. Also, the television or stereo may be set at a volume setting that is too loud for the user to engage in conversation via the telephone handset. This situation typically requires the user to move away from the television or stereo speakers in order to reduce the effect of the television or stereo on the telephone conversation. Alternatively, the user may elect to reduce the volume setting or mute the volume setting of the television or stereo. To achieve this volume control, the user may attempt to locate the remote control unit associated with the television or stereo at the same time the user is locating the cordless telephone handset. Further, the user may attempt to control the volume setting of the television or stereo via the remote control unit (typically by pressing one or more buttons on the remote control unit), while answering the incoming telephone call (typically by pressing a button on the cordless telephone handset). This can be a difficult maneuver which may result in the user accidentally disconnecting the telephone call.
Further, although the user may subscribe to a caller ID service, through which call related information is provided with incoming telephone calls, the caller ID information may be displayed at the location of the base unit or may be difficult to see during low illumination television viewing. This situation may cause the user to elect to answer a call the user otherwise would not have answered, which can be a problem in and of itself, and may further be a problem if answering the call causes the user to unnecessarily interrupt a potentially important television viewing moment.